Azido formates

ABSTRACT

Disclosed is a process of improving the adhesion of polyester material to various other materials using the azidoformates of omega-hydroxyalkyl phthalates, their related low molecular weight condensation polymers and their mixtures represented by the general formula   WHERE R is an alkylene radical containing 2 to 10 carbon atoms and x is an integer of from about 1 to about 10. In particular, there is disclosed a process of improving the adhesion of polyester tire cord to rubber tire stock using the said azidoformate compounds.

United States Patent [191 Haynes 1 Oct. 21, 1975 1 AZIDO FORMATES [75]Inventor: James N. Haynes, Wilmington, Del.

[73] Assignee: Hercules Incorporated, Wilmington,

Del.

[22] Filed: Feb. 12, 1975 [21] Appl. No.: 549,229

Related US. Application Data [60] Division of Ser. No. 425,906, Dec. 18,1973, which is a division of Ser. No. 231,741, March 3, 1972, Pat. No.3,814,657, which is a division of Ser. No. 93,399, Nov. 27, 1970, Pat.No. 3,686,231, which is a continuation-in-part of Ser. No. 887,382, Dec.22,

1969, abandoned.

Primary ExaminerLewis Gotts Assistant Examiner-D. R. Phillips Attorney,Agent, or Firm-Marion C. Staves [57] ABSTRACT Disclosed is a process ofimproving the adhesion of polyester material to various other materialsusing the azidoformates of omega-hydroxyalkyl phthalates, their relatedlow molecular weight condensation polymers and their mixturesrepresented by the general formula where R is an alkylene radicalcontaining 2 to 10 carbon atoms and .r is an integer of from about 1 toabout 1.0. In particular, there is disclosed a process of improving theadhesion of polyester tire cord to rubber tire stock using the saidazidoformate compounds.

1 Claim, No Drawings AZIDO FORMATES This application is a division of mycopending application Ser. No. 425,906, filed Dec. 18, 1973, whichapplication is a division of copending application Ser. No. 231,741,filed Mar. 3, 1972, now U.S. Pat. No. 3,814,657, which application is adivision of application Ser. No. 93,399, now US. Pat. No. 3,686,231,which application is a continuation-in-part of application Ser. No.887,382, filed Dec. 22, 1969, now abandoned.

This invention relates to a new class of organic compounds and tocertain uses for the new compounds. In particular, this inventionrelates to the azidoformates of omega-hydroxyalkyl phthalates and theirrelated low molecular weight condensation polymers and their mixtures,their use in modifying polyester material to provide improved adhesionand to the products so produced.

Attempts have been made in the past to adhere polyester material toother materials such as other polymers, resins, silicious materials,metals, metal oxides, wood, paper, cloth, etc. However, such attemptshave been only partially successful because the said materials do notadhere well to polyesters.

It has now been found that the adhesion of polyester materials, i.e.,polyesters obtained by reacting glycols with dicarboxylic acids, can begreatly improved by modifying the surface of said polyester materialwith an omega-hydroxyalkyl phthalate azidoformate.

The novel and unique omega-hydroxyalkyl phthalate where R is an alkyleneradical containing 2 to 10 carbon atomsand x is an integer of from about1 to about 10. [t is to be understood that the term omegahydroxyalkylphthalate azidoforinates as used in the specification and claims of thisapplication includes not only the pure compounds, but mixtures of the0-, mand psubstituted phthalates and their related low molecular weightcondensation polymers as well as mixtures thereof. The azidoformatecompounds of this invention range from liquids to solids at roomtemperature and atmospheric pressure and have characteristic infraredspectra, containing a strong azide band at about 2140 cmf, and a strongcarbonyl band at around 1740 cm..

The omega-hydroxyalkyl phthalate azidoformates of this invention can beprepared by various methods. For example, they can be prepared from thecorresponding hydroxyl terminated low molecular weight condensationproducts of a glycol and either 0-, m-, or p-phthalic acid or a mixedphthalic acid. The hydroxyl terminated compounds can be prepared by atransesterification reaction using a dimethyl ester of a phthalic acidand a glycol. As indicated above, the ester of phthalic acid can be apure o-, mor p-isomer, but more likely will be an ester of mixedisomers. Various straight chain glycols containing 2 to 10 carbon atoms,such as ethylene glycol, propylene glycol, butylene glycol, hexylenegl-ycol, octylene glycol and nonene glycol can be used. Thetransesterification reaction between the dimethyl ester ofa phthalicacid and a glycol can be shown in the following general equation:

azidoformates of this invention are represented by the 40 where R is asdefined above. As the transesterification general formula reactionprogresses the amount of free alkylene glycol diminishes and the amountof diglycol phthalate in- 0 0 (l! u creases, giving rise to thepossibility of low molecular 0 5 weight condensation polymers and theirmixtures. N OR--Ol.

Thus, the above general equations can be modified as X follows:

i ii if C O--CH q C O-ROH CH3OC +2HO-R-OH o HO-RO-C +2CH3OH l i iic-o-cii, COROH O O CH;,-Oll +HOROH ci-i, o c +cii,oHT

W H q C--OR-O-C (I) HO-ROC c o R 0ii where R is as defined above. Itwill be apparentto those skilled in the art that the transesterificationreaction will give rise to still higher molecular weight condensationproducts and usually will result in a mixed product. While it is quitepossible to obtain a product 80 or even 90% pure, it is very difficultto obtain a completely pure product. The product or products of thetransesterification reaction can be treated with phosgene to produce thecorresponding chloroformate or chloroformates. The reaction can be shownas follows:

where R and x are as defined above. The resulting chloroformate is thentreated with an excess of sodium azide to form the azidoformate groups.The reaction of the hydroxy terminated compound with phosgene is usuallycarried out at a temperature of from about 0C. to about C. in an inertsolvent such as methylene chloride, ethylene dichloride, toluene orxylene. The reaction with sodium azide is generally conducted at atemperature of about to about C. in a mixed solvent such asacetone-water, methylene chlorideacetone-water, orbenzene-acetone-water.

As indicated above, this invention includes the use of the uniqueomega-hydroxyalkyl phthalate azidoformates in modifying polyestermaterials to provide improved adhesion to various other materials. It isbelieved that the advantageous properties of these azidoformates are dueto their similarity in chemical composition to the polyesters which theyare used to modify.

The polyester materials modified in accordance with the instantinvention are made from the well-known polyesters obtained by reactingglycols, such as ethylene glycol, propylene glycol,cyclohexanedimethylol, and the like with dicarboxylic acids, such asterephthalic acid, isophthalic acid, stilbene dicarboxylic acid, and thelike, such as shown in U.S. Pat. No. 3,057,823 or 3,424,727. Thepolyester can be in any form, including extruded, molded, spun, cast,etc., blocks, sheets, film, fiber, yarn, cord and woven and nonwovenfabrics. Included also are polyesters which have been reinforced, suchas, for example, a polyester reinforced with glass fibers. In the caseof yarn, fabric or cord made from polyester fibers, combinations orblends of polyester fibers with, for example, cotton or rayon fibers canbe used in this invention. Improved adhesion of polyester fibers toother materials can be obtained by the process of this invention nomatter what the physical form of these fibers. However, as a practicalmatter the fiber to be modified generally will have been I previouslytwisted or plied into yarn or cord or may.

have been woven or knit into fabrics. Various methods for thepreparation of blocks, sheets, film, fiber, yarn, cord, and woven andunwoven fabrics of polyesters are well known to those skilled in theart.

The modification of polyester materials by treatment with anomega-hydroxyalkyl phthalate azidoformate is accomplished by contactingthe polyester with an omega-hydroxyalkyl phthalate azidoformate as, forexample, by dipping, spraying, brushing or running it over a coated rollwith a solution or dispersion of the azidoformate in a suitable liquid.Examplary of suitable organic solvents for the azidoformate compoundsare to]- uene, benzene, acetone, methylene chloride, trichloroethylene,and the like. In addition to the organic solutions above mentioned,finely divided particles of the azidoformate compounds can be dispersedin water using surface active agents. Next, the thus contacted polyesteris heated to a temperature above the decomposition point of theazidoformate groups resulting in surface modification of the polyester.This temperature will vary depending upon the period of time thematerial is heated. Thus, a temperature of about 200-250F. can be usedif the material is to be heated for several minutes, while a temperatureof about 450F. is required if the material is to be heated for less thana minute. In general the temperature will be from about 200F. to about500F. Various amounts of the omega-hydroxyalkyl phthalate azidoformatecompounds can be used. The optimum amount will depend upon the amount ofmodification desired and the specific azidoformate compound used. Ingeneral, the amount added based on the weight of the polyester will befrom about 0.1 to about 5%.

As indicated above, the azidoformate modified polyester materialsexhibit a much greater adhesion for other materials. Typical of theother materials which can be adhered to or to which the modifiedpolyesters will adhere are other polymers such as the hydrocarbonpolymers including polystyrene, styrene-butadiene rubber, butyl rubber,natural rubber, polybutadiene, polyisobutylene, cis-l ,4-polyisoprene;and the nonhydrocarbon polymers including the cellulose esters such ascellulose acetate butyrate, acetate rayon; cellulose partial alkylethers such as hydroxyethyl and hydroxypropyl cellulose; drying andnon-drying alkyd resins; poly(alkylene oxides) such as poly(propyleneoxide); poly(arylene oxides) such as poly(phenylene oxide); thepolyamides such as nylon, perlon-L; poly(vinyl alkyl ethers) such aspoly(vinyl methyl ether); vinyl chloride polymers such as poly(vinylchloride), vinyl chloride-vinyl acetate copolymers, vinylchloridevinylidene chloride copolymer, vinyl chloride-maleic anhydridecopolymer, vinyl chloride-vinyl acetal copolymers, vinyl chloride-vinylacetate-maleic anhydride terpolymer; chlorinated natural rubber;ethylenevinyl acetate copolymers; poly(vinylidene chloride); vinylidenechloride-acrylonitrile copolymer; poly(ethyl acrylate); poly(ethylmethacrylate); epoxy resins; epoxy polymers such aspoly(epichlorohydrin); poly[3- ,3-bis(chloromethyl)oxetane];polychloroprene; butadiene-acrylonitrile copolymer andbutadieneacrylonitrile-styrene terpolymer; cellulosics such as wood,paper and cotton; siliceous materials such as glass, asbestos, sand,clay, concrete, stone, brick and ceramic materials; metals such asaluminum, cadmium, chromium, copper, iron, magnesium, nickel, tin,titanium and zinc, andalloys of the metals such as brass,

bronze, steel and nickel chrome; and including metals and alloys whichhave been surface treated with phosphates, chromates, etc.; metal oxidessuch as aluminum oxide, iron oxide, lead oxide, titanium dioxide andzinc oxide, and the conventional coating compositions such as the alkydresin based coatings, epoxy based coatings and urethane based coatings.

In many cases, particularly in structural bonding, it is desirable touse adhesives and bonding cements between the modified polyester andmaterial to which it is to be bonded. Typical of the adhesives andcements which bond tightly to the modified polyesters are the cellulosicadhesives such as cellulose acetate, cellulose nitrate and methylcellulose; natural rubber-based adhesives; nitrile-rubber cements suchas those based on acrylonitrile-butadiene copolymers; carboxylicelastomer adhesives such as those based on vinyl chloridevinylacetate-maleic anhydride terpolymers, ethylacrylate-acrylonitrile-acrylic acid terpolymers or butadiene-methacrylicacid copolymers; neoprene cements, both curing and non-curing;polysulfide adhesives such as the reaction products of polysulfideliquid polymer with an epoxy resin, phenol-aldehyde resin adhesives suchas phenol-formaldehyde resins and resorcinolformaldehyde resins; aminoresin adhesives such as urea-formaldehyde resins andmelamine-formaldehyde resins; epoxy resin adhesives such as the resinresulting from the condensation of epichlorohydrin and bisphenol-A;isocyanate-based adhesives, vinyl polymer adhesive such as polyvinylacetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl formal,polyvinyl methyl ether, polyvinyl ethyl ether and polyvinyl isobutylether; cyanoacrylate adhesives such as methyl 2- cyanoacrylate;polyamide adhesives such as the thermoplastic reaction products ofdibasic acids with diamines or the thermoset reaction products ofpolyamide resins with epoxy resins; and unsaturated polyester adhesivessuch as the resin resulting from the reaction of maleic anhydride and1,2-propylene glycol.

The specific adhesive or bonding cement which may be used will dependupon the material to be bonded to the modified polyester. For example,in bonding a polyester to rubber, such as bonding fibrous polyesterreinforcing material to rubber, the use of an industrial adhesive ismost advantageous. The adhesive will generally be a mixture of aphenol-aldehyde resin and a vinylpyridine polymer latex. The exactselection of the polymer latex components will be made to achievecompatibility with the rubber used in the final polyester-to-rubbercomposite. Preferably, the phenolaldehyde resin will be prepared fromresorcinol and formaldehyde, although other phenols such ashydroxybenzene, paracresol, and pyrogallol can also be used. The moleratio of phenolic compound to aldehyde in the phenol-aldehyde resin canbe varied between about l:l.02 to about 1:5. The phenol-aldehyde resinwill generally be aged for a period of from about 0.5 to about 6 hoursbefore mixing with a vinylpyridine polymer latex. The said aging can becarried out at room temperature or elevated temperatures. For use withnatural rubber and styrene-butadiene rubber the vinylpyridine polymerlatex will preferably be a terpolymer of a vinylaryl monomer, a dienemonomer, and a vinylpyridine monomer. The vinylaryl monomer willpreferably be styrene, although other monomers such as vinyltoluene canbe used. The diene monomers which can be used-in preparing the polymerlatex are openchained conjugated diolefins, including, for example,1.3-butadiene, isoprene, 2,3-dimethyl-l,3-butadiene,1,2-diethyl-l,3-butadiene and piperylene. The vinylpyridine monomersmost useful in preparing the poly 5 mer latex are alpha-vinylpyridine,5-ethyl-2- vinylpyridine, and 2-methyl-5-vinylpyridine. Thevinylpyridine content of the terpolymer is usually from about 5% toabout 25%. The vinylaryl monomer content is from about 5% to about 35%and the diene monomer content from about 50% to about 85%. The polymerlatex can be admixed with the phenol-aldehyde resin at ratios betweenabout 2:1 and about :1. Following the mixing of the two ingredients thepH will generally be adjusted to about 9.5 to about 10.5 using aninorganic base such as ammonium hydroxide.

The modified polyester material can be coated with the conventionalindustrial adhesive coating uniformly by dipping, spraying, running thematerial over a coated roll, or other conventional procedure. Theadhesive coating will amount to from about 2% to about 10% by weight ofthe material. The adhesive coated material will then be cured for ashort time such as from about 1 to about 10 minutes at a temperaturebetween about 200F. and about 500F. The cured adhesive coating is a hardpolymer which is very adherent to the modified polyester material andproduces excellent adhesion between the modified material andconventionally vulcanized rubber. It may be desirable in certain casesto omit the latex adhesive coating thereby directly adhering themodified polyester material to a vulcanizable rubber stock and curing toobtain a bonded rubber product. Such products bonded to modifiedpolyester material are superior to products bonded to non-modifiedpolyester material, but may exhibit a proportionate decrease in adhesivestrength over those bonded to modified polyester material coated withthe above described coating composition.

Finally, the adhesive coated modified fibrous polyester material can bebonded to a vulcanizable rubber stock by embedding the reinforcingmaterial in the vulcanizable rubber stock and curing. Conventionalvulcanization temperatures in the order from about 250F. to about 350F.can be used. The modified fibrous polyester material of this inventioncan be used as reinforcement in any type of polymer material or mixturesor blends of polymer materials with suitable fillers, pigments,antioxidants, and crosslinking (i.e., vulcanizing) agents such assulfur, dicumyl peroxide, and the like. Typical of the uses of themodified fibrous polyester material is in reinforcing rubber tires,including automobile, truck, tractor, and aircraft tires, as well as inrubber belting and rubber hose where low elongation, strength anddimensional stability are important.

In the case of bonding metal to modified polyester, one can use an epoxytype adhesive such as a resin of bisphenol-A and glycidyl ether curedwith a polyamide with free amino functionality. Another metal-modifiedpolyester adhesive is a phenolic-polyvinyl butyral type adhesive. Stillother adhesives for metal-modified polyester bonding will be obvious tothose skilled in the art.

In the case of bonding siliceous materials such as glass to a modifiedpolyester, one can use a polyvinyl acetal type adhesive such as apolyvinyl butyral-phenol type adhesive. Where the glass is in the formof fibers for reinforcement of polyester material, the bond between thefibers and polyester can be improved b EXAMPLE 1 This exampleillustrates the preparation of betahydroxyethyl terephthalateazidoformate.

To a solution of parts of beta-hydroxyethyl terephthalate chloroformatein a mixed solvent comprising 79 parts of acetone and 133 parts ofmethylene chloride is added twenty parts of sodium azide at roomtemperature. The resulting mixture is stirred for approximately 6 hoursand then stripped of solvent under a vacuum. The resulting product,consisting essentially of beta-hydroxyethyl terephthalate azidoformate(at least 90% pure), has a melting point of 8587C. An infrared spectrumof this product shows a strong azide peak at 2140 cm'f A typicalelemental analysis of this product is:

Calculated Found EXAMPLE 2 This example illustrates the preparation ofbetahydroxyethyl isophthalate azidoformate.

To a solution of 99 parts of beta-hydroxyethyl isophthalatechloroformate in a mixed solvent comprising 266 parts of methylenechloride and 79 parts of acetone, is added 65 parts of sodium azide. Theresulting slurry is stirred for 15 hours at room temperature, filteredand the solvent removed under vacuum. The resulting product (91% oftheoretical) consists essentially of beta-hydroxyethyl isophthalateazidoformate (at least 90% pure). An infrared spectrum of this productshows a strong azide peak at 2140 cm.. A typical elemental analysis ofthe product is:

Calculated Found EXAMPLE 3 EXAMPLE 4 This example illustrates thepreparation of betahydroxyethyl isophthalate dimer azidoformate havingthe following general formula:

8 i ii To a solution of 54 parts of beta-hydroxyethyl isophthalate dimerchloroformate in a mixed solvent of acetone and methylene chloride isadded 66 parts of sodium azide at room temperature. The resultingmixture is stirred for approximately 6 hours and then stripped ofsolvent under a vacuum. The resulting product, consisting of more than80% beta-hydroxyethyl isophthalate dimer azidoformate, is a clearcolorless viscous oil. A typical elemental analysis of the productCalculated Found C 49.4 49.9 H 3.4 3.8 N 14.4 13.8

EXAMPLES 5, 6, 7 & 8

These examples show the bonding of polyester tire cord to rubber tirestock using the beta-hydroxyethyl phthalate azidoformate compounds ofExamples 1-3 and the beta-hydroxyethyl isophthalate dimer azidoformateof Example 4.

In each case poly(ethylene terephthalate) tire cord, 1000 denier and3-ply under about 500 grams of tension is passed twice through a troughcontaining a 5% solution of the azidoformate compound intrichloroethylene. The cord is next passed through two ovens in seriesat 200F. and 350F. Residence times in the ovens are 65 and 54 secondsrespectively. The cord dip pickup is approximately 2% by weight in eachcase.

The modified cord is next dipped in a resin latex prepared as follows:To a solution of 0.24 part of sodium hydroxide in 192.8 parts of wateris added 8.8 parts of resorcinol with continued stirring until acomplete solution is achieved. Then 12.2 parts of 37% formaldehyde isadded. The solution is aged for approximately 5 hours at about C. andthen added slowly to a mixture of 48 parts of water and parts of acommercial latex comprising a 41% solids terpolymer of styrene,butadiene and vinylpyridine, the monomers being present in a ratio ofapproximately 15:70:15. The mixture is stirred slowly for 15 minutes andits pH adjusted to 10.3 using concentrated ammonium hydroxide. Theresulting gray-violet latex contains approximately 20% solids. Theazidoformate modified cord is passed twice through a trough of theabove-described tire cord coating under a tension of 500 grams and thendried and cured for 54 seconds at a temperature of 430F. The cord dippick-up is approximately 4.5% by weight in each case. p y

The thus coated cord is then embedded in a vulcanizable rubber tirestock and cured in the form of 3/8 H- specimens. The rubber tire stockhas the following formulation:

Compounds Parts Natural rubber (smoked sheet) 80 Styrene-butadienerubber 20 Semi-reinforcing furnace black 25 Zinc Oxide Stearic Acid 2Polytrimethyldihydroquinoline 1 Heavy Pine Tar 0.5 BenzothiazoleDisulfide l Tetramethyl Thiuram Disulfide 0.1 Sulfur 2.6

The test specimens are cured for 45 minutes at a temperature of 307F.After several hours conditioning at room temperature the H-specimens aretested according to the procedure of ASTM D-2138-62T. A control specimentreated exactly the same as described above is also tested. The resultsof the test are tabulated below:

Pounds to Failure Example Azidoformate Treatment (Average of Six' Tests)Control None 12.6

5 Beta-Hydroxyethyl terephthalate azidoformate 47.0 6 Beta-Hydroxyethylisophthalate azidoformate 46.0 7 Beta-Hydroxyethyl orthophthalateazidoformate 43.0 8 Beta-Hydroxyethyl isophthalate Dimer azidoformate45.0

EXAMPLE 9 This example shows the bonding of polyester tire cord torubber tire stock using an aqueous emulsion of beta-hydroxyethylisophthalate azidoformate.

A 20% emulsion is formed by heating 200 parts of beta-hydroxyethylisophthalate azidoformate to 80C. at which temperature it is quiteliquid, and adding with stirring approximately 400 parts of water heatedto 90C. and containing 10 parts of sodium lauryl sulfate surface activeagent. An additional 400 parts of hot water is added and the mixturehomogenized.

Poly(ethylene terephthalate) tire cord,. 1000 denier and 3 ply ismodified using the azidoformate emulsion, heated, coated with a resinlatex, embedded in a vulcanizable rubber tire stock and cured in theform of H-specimens all as described in Examples 5 to 8. The testspecimens are tested according to the procedure of ASTM D-2138-62T. Anaverage (6-test specimens) of 30.2 pounds is required to overcome thetire cordrubber adhesion. Control specimens treated exactly the same wayexcept for the azidoformate compound treatment give an average of 12.6pounds to overcome the tire cord-rubber adhesion.

EXAMPLE 10 This example shows the surface modification of polyesterplaques and their bonding with an epoxy adhesive.

Injection molded glass reinforced poly(ethylene terephthalate) plaques,about 4 X 4 inches by Va inch thick and containing approximately 30% byweight of glass having an epoxy equivalent of about 180-185 andconreinforcing fibers are sprayed with a 10% solution ofbeta-hydroxyethyl isophthalate azidoformate in toluene. The solvent isevaporated off and the coated plaques heated for 4 minutes at atemperature of 180C. A light'yellow tack-free coating results whichadheres tenaciously to the plaque surface. The add-on of theazidoformate primer is approximately 1 mg. per sq. inch. l

The thus modified plaques are coated with a liquid epoxy adhesive of thebisphenol A-glycidyl ether type,

taining approximately 10 parts per hundered of triethylene tetramine.The adhesive coated surfaces of the plaques are pressed together, with a1 inch overlap, using approximately 50 lbs. pressure and cured for 30minutes at a temperature of C. The adhesive layer between the plaques isapproximately 1 mil in thickness. A control laminate is prepared in anidentical way except the azidoformate priming step is omitted.

Lap shear tests according to ASTM D1002 are performed on 1 inch widesamples of the modified plaque laminate and control. The azidoformateprimed laminate fails at approximately 700'lbs./sq. in. due to thebreaking of the plaque along the bond edge. The control fails atapproximately lbs./sq. in. with adhesion failure at the interface.

EXAMPLE 1 1 This example shows the bonding of polyester plaques tocold-rolled steel.

An injection moldedglass'reinforced poly(ethylene terephthalate) plaqueas described in Example 10 is modified with beta hydroxyethylisophthalate azidoformate exactly as described in Example 10. The thusmodified plaque and a 4 X 4 inch sheet of cold-rolled steel 0.063 inchthick, which had been cleaned and degreased in trichloroethylene, arecoated with a liquid epoxy adhesive of the bisphenol A-glycidyl ethertype, having an epoxy equivalent of about 185 and containingapproximately equal parts by weight of a polyamide with free aminofunctionality. The adhesive coated surface of the plaque is pressedagainst the adhesive coated surface of the steel sheet, with a 1 inchoverlap, using approximately 50 lbs. pressure and cured for 30 minutesat a temperature of 140C. The adhesive layer is about 1 mil inthickness. The strength of the bond as determined in lap shear testsaccording to ASTM D1002 is greater than 1150 lbs/sq. in.

EXAMPLE 12 This example shows the use of various adhesives in bondingmodified polyester materials.

Poly(ethylene terephthalate) film 5 mils thick is coated and modifiedwith beta-hydroxyethyl isophthalate azidoformate as described in Example10. Samples of the thus modified film are bonded to modified glassreinforced plaques, prepared as described in Example 10, by coating themodified surface of each film and plaque with an adhesive as describedbelow. Controls are prepared using unmodified glass reinforced plaques.Specimens of the laminates are tested for 180 peel strength and theresults tabulated below:

Table 1 Modified Film Modified Film and and Adhesive Adhesive CureModified Plaques Unmodified Plaques Epoxy 140C. for Film failed be-Adhesive failure Adhesive 30 minutes fore joint at interface Polyester130C. for Film failed be Adhesive failure Adhesive 30 minutes fore jointat interface Polyester 130C. for Film failed be- Adhesive failureAdhesive 30 minutes fore joint at interface Polyester I30C. for Filmfailed be- Adhesive failure Adhesive 30 minutes fore joint at interfaceRuhbcr- Room temp. Cohesive fail- Adhesive failure based Ad-' v ure ofadat interface hesive hesivc Bisphenol A-glycidyl other type describedin Example I l.

Saturated polyester type sold under the name "Vitel PE 207", modifiedwith polyisocyanate cross-linker.

Saturated polyester type sold under the name DuPont polyester 49.650".modified with polyisoeyanate cross-linker.

Saturated polyester type sold under the name Bostik 7902". modified withpolyisocyanate cross-linker.

-" Rubber-based cement sold under the name Conhond".

What I claim and desire to Protect y Leuefs Patent where R is analkylene radical containing 2 to caris: bon atoms and x is an integerfrom 1 to 10.

1. An omega-hydroxyalkyl phthalate azidoformate having the formula O 0II II C O-ROCN;, 0 0 u u y m-C ORO-C

1. AN OMEGA-HYDROXYALKYL PHTHALATE AZIDOFORMATE HAVING THE FORMULA